Single lumen microcatheter for executing plugs near distal terminus of lumen

ABSTRACT

Micro-catheters and embolic agents offer better results in endovascular treatment of brain arteriovenous malformations. Using said micro-catheters and embolic agents generally requires the creating of a plug at the distal-most portion of said micro-catheters which regularly results in suboptimal results. The present invention teaches how to create and use a device which creates a plug downstream of the distal-most portion of said micro-catheters and thereby ameliorates the suboptimal outcomes associated with creating a plug at the distal-most portion of said micro-catheters.

CROSS-REFERENCES

This utility patent application claims the benefit of the priority date of provisional application Ser. No. 62/600,137 filed Feb. 13, 2017 (13-Feb.-2017).

FEDERALLY FUNDED R&D

None

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates in general to medical equipment and procedures. In particular, the invention relates to catheters for use in performing certain medical procedures, such as the treatment of brain arteriovenous malformations includes endovascular embolization, surgical resection, and stereotactic radiotherapy, alone or in combination.

The present invention is a tool to more safely and more effectively implement endovascular treatment of arteriovenous malformations and arteriovenous fistulas, reducing procedural times and exposure to X-ray radiation to the patient and the treating staff.

Background Art

Treatment of brain arteriovenous malformations includes endovascular embolization, surgical resection, and stereotactic radiotherapy, alone or in combination. In the past, n-butyl cyanoacrylate (nBCA) was used as an adjunct to surgery; however, introduction of a dimethyl sulfoxide (DMSO)-based embolic agent, Onyx (ev3, Covidien), and more recently in other countries, PHIL™ (Precipitating Hydrophobic Injectable Liquid, MicroVention® Terumo) and SquidPERI (EVOH, by emboflu, Switzerland), and advancement in micro-catheter design often offered better endovascular results in brain arteriovenous malformations treatment. Liquid embolic agents are the preferred embolic material in endovascular treatment of pial and brain arteriovenous malformations and dural arteriovenous fistulas. Advancements in micro-catheter design and emergence of new embolic agents offer better results in endovascular treatment of brain arteriovenous malformations.

Among said advances is the use of dual lumen devices which employ one lumen to dispense a balloon to block Onyx flow and a second lumen to deploy Onyx. Said prior art teaches that double-lumen versions are more efficient than single-lumens because double-lumen allow simultaneous execution of tasks.

The reduction from two lumens (note: for medical devices, a luminous term referring to the channel within a tube) to one is non-obvious. In particular, the prior art related to lumens teaches that double-lumen versions are more effective single-lumens for managing unexpected as well as anticipated difficulties. Additionally, the prior art related to lumens teaches that double-lumen versions are more efficient than single-lumens because double-lumen allow simultaneous execution of tasks. Thus, the prior art teaches away from reducing lumens generally and specially teaches away from single-lumens.

The prior art contains several catheters with a hole in addition to the end hole. Most of these are taught by twelve patents: U.S. Pat. No. 9,440,043 (Arora et al.); U.S. Pat. Nos. 9,399,112; 9,364,634; 8,496,629; 8,403,911; 6,223,637; 5,954,687; 5,800,407; 5,180,387; 4,970,926; 4,784,638; and 4,755,176.

However, most are designed to drain cerebrospinal fluid from the ventricular through a catheter that enters through a hole in the skull and would not be capable of injecting glue into an artery that enters through the femoral artery and is snaked up through blood vessels in the body. Additionally, the inventions described in said patents could be used to inject something directly into the brain and/or ventricle. However, they could not be used to inject something into an artery within the brain, or to provide a temporary arterial bypass. If it were introduced directly into the artery through the brain it would undoubtedly cause a life threatening bleed in the brain. The medical basis is that a catheter designed to be inserted directly into the brain has no possible role for an intravascular application.

Additionally, the structure of the devices taught by said twelve patent differs from the structure of the present invention. In particular, U.S. Pat. No. 9,440,043, which is a catheter having a tapered structure and balloon formed above a lower drainage hole differ from the present invention because it has a balloon which covers the distal end hole and the present invention does not. U.S. Pat. No. 9,399,112 is a catheter hole having an inclined trailing edge while the present invention does not have an angled side hole. U.S. Pat. No. 9,364,634 teaches an embedded co-extrusion for improving catheter hole array efficiency, whereas the present invention does not use co-extrusions. U.S. Pat. No. 8,496,629 is a catheter which uses staggered diffusion holes a flow breaking feature, the present invention does not require any flow breaking feature. Similarly, U.S. Pat. No.8,403,911 uses diffusion side holes to improve catheter efficiency, while the present invention does not require any flow breaking feature, including diffusion side holes. U.S. Pat. No. 6,223,637 is a catheter side-wall hole cutting apparatus, whereas the present invention while capable of deploying a device to cut a catheter side-wall has neither a suction element nor a cutting element. U.S. Pat. No. 5,954,687 teach the use of a fluid reservoir, however the present inventions does not. U.S. Pat. No. 5,800,407 is a multiple hole epidural catheter which teaches the use of both permanently opened and permanently closed holes, whereas the present inventions uses holes which can be both opened and closed on a temporary basis in addition to holes which are permanently open. Furthermore, the present invention is designed for intravascular, not epidural use. U.S. Pat. No. 5,180,387 teaches the use of angled holes in a catheter with a non-circular bore, the present invention teaches non-angled holes in a circular bore.

U.S. Pat. No. 4,970,926 teaches an apparatus for making angled hole ventricular catheter which uses a plurality of rods with an end hole in each, where as the present invention teaches the use of side holes. The '638 shows is an angled hole ventricular catheter designed for extended impartment in the brain, whereas the present invention does not use angled holes and is not intended for extended impartment in the brain. U.S. Pat. No. 4,755,176 teaches a catheter with side hole in one of two lumens, whereas the present invention is a single lumen device.

The art prior to the inventor's other disclosures suffers from several significant shortcomings. These include difficulty forming a proximal “plug” before too much distal Onyx prevents a subsequent ejective distal “push”, too much reflux of Onyx along the micro-catheter, approaching a normal branch artery, necessitating aborting that injection for safety concerns. Other shortcomings include slow plug formation, and the need for longer procedures necessitating longer fluoroscopic times and higher radiation doses.

The prior art also fails to adequately address the fact that during the initial “plug” injection(s) of Onyx 34 (after lacing the micro-catheter with dimethyl sulfoxide) are off target. Consequently some of the plug material ends up in the distal most tip of the micro-catheter (beyond the side hole). Additionally, typically the plugging material, such Onyx 34, when in contact with blood that is not moving will then start to solidify in the tip of the micro-catheter, and can obstruct it. An obstructed, distal penetration of the lesion being treated with the embolics agent is no longer possible

An improved liquid embolic agent delivery system is required to ameliorate said difficulties. It appears that the present invention is an excellent alternative to existing embolic agent delivery systems because it allows said ameliorations. In particular, it is easier to use than existing delivery systems, allows faster plug formation, and requires less procedural time and X-ray/radiation dosage; it is also more consistently effective.

Said micro-catheters and embolic agents often require creating a plug at the distal-most portion of said micro-catheters in order to facilitate optimal subsequent embolic penetration. Typically, treatments are suboptimal when there is difficulty forming a “plug”. Said difficulties can result in liquid embolic failure to penetrate the target area, such as a fistula's nidus.

SUMMARY OF INVENTION

The present invention teaches how to create and use a device which facilitates creation of a plug or plug-equivalent near but proximal to the distal end hole of said micro-catheters, thereby ameliorating the difficulties in creating said plug utilizing current technologies.

The present invention is a single lumen micro-catheter with a single or multiple side holes a set short distance from the end hole (typically 5 mm-30 mm). The hole positioning is designed to allow the more viscous Onyx 34 (or higher viscosity versions of MicroVention's Precipitating Hydrophobic Inject-able Liquid, or similar liquid embolic agents) be delivered more proximately to a targeted location. This novel delivery would allow the formation of a proximal “plug” more easily.

As a result of such targeted delivery of a “plug”, less viscous Onyx 18 (or similar) consequently can then be more easily “pushed” into an AVM nidus or another target lesion more effectively. This results in better distal lesion penetration, and less chance of unwanted proximal reflux.

Some embodiments of the present invention incorporate valve technology to control Onyx flow. Said valve technology uses either semi-permeable material to control of selected fluids by employing selectively permeable, or non-permeable material to control flow, or a combination. The selective flow control valve embodiment of the current invention can be set with fixed flow through area. The variable flow control valve embodiment of the current invention allows variable flow control area. Said variability of flow area is capable of responding to changes in pressure, fluid viscosity, magnetic field or combination thereof, or other differential conditions.

Some embodiments of the present invention incorporate differential inner diameter sizing of a catheter, together with a wire, to allow flow of liquids and/or liquid embolic through the majority of the catheter and out the distal “side hole”, while preventing unwanted early filling of the distal-most portion of the catheter beyond the side hole.

For example, the micro-catheter up to the side hole may have an ID of 0.014″, and beyond the side hole it may have an ID of 0.007″. Once the micro-catheter is in the desired position for embolization, DMSO followed by Onyx 34 can be injected with a wire in the catheter to create a “plug” at the side hole. The wire completely obstructs the portion of the catheter distal to the side hole, which has an ID that matches the OD of the wire, thus preventing Onyx from entering that segment of the catheter before desired, and possibly hardening within that portion of the catheter and obstructing it. Once an adequate “plug” has been formed, the wire can be removed and Onyx 18 (or similar) can be “pushed” out the distal hole of the catheter and into the target lesion.

Another embodiment of the present invention does not have a side hole. Instead, at a similar location along the distal portion of the catheter, it has a thin layer of hydrogel adhered along the entire circumference of the catheter. The hydrogel can be such that it expands after a certain amount of time exposed to blood, or with a certain electrical magnetic signal, or with infusion of a certain triggering liquid, or other trigger. Once the catheter is in the desired position, the hydrogel can be expanded, and the hydrogel will act as a “plug” to prevent reflux of liquid embolic such as Onyx 18, when it is injected through the catheter and out the distal end hole.

All versions can have a “detachment” zone at a desired location, in some embodiments. In such embodiments, the end of the catheter near the distal end hole may detach after injection of liquid embolic, in certain circumstances, similar to the EV3/Medtronic Apollo detachable tip micro-catheter.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of the single lumen catheter of the current invention depicting a side hole, untapered end, a distal end hole, proximal catheter hole, and an optional microwire.

FIG. 2 depicts the embodiment of FIG. 1, further including a breakaway or detachment element near the proximal side of the side hole, and a tapered end.

FIG. 2A depicts the embodiment of FIG. 2, further depicting optional microwire 60 disposed within breakaway or detachment element 110 in an uncoupled state.

FIG. 3 depicts the embodiment of FIG. 2 without the optional microwire.

FIG. 4 is a perspective view of the current invention further depicting a governing element proximal to the distal end.

FIG. 5 depicts the embodiment of FIG. 4, further including a breakaway or detachment element proximate to the proximal side of the governing element.

FIG. 6 is a perspective view of an alternate embodiment of the single lumen micro-catheter of the current invention depicting a zone of hydrogel coated on the exterior circumference proximal to the distal end instead of a side hole.

FIG. 7 depicts the embodiment of FIG. 6, further including a breakaway or detachment element 110 proximate to the proximal side of the hydrogel zone.

DETAILED DESCRIPTION OF THE INVENTION

The present invention uses an existing lumen element for a novel purpose. In particular, the present invention uses a hole on the side of a single-lumen micro-catheter (hereinafter “side hole”) for preparing a plug. While use of at least one side hole has been taught, the teaching had several potential limitations, as described above. FIG. 1 depicts the most basic version of the catheter, untapered, with a single side hole, but no governing valve. Alternatively, there may be multiple circumferential holes disposed about the same segment of the catheter.

The novel use of side hole 20 is to build a plug proximal to the distal-most end hole 40 of the catheter. Said plug, when successfully deployed would prevent unwanted reflux of Onyx (or similar or equivalent), and would facilitate better distal penetration of the lesion. However, in many cases there is a need to prevent the flow of Onyx beyond the distal side hole within the catheter, before the “plug” is fully formed. Said prevention of premature flow ameliorates possible unwanted occlusions of the distal-most segment of the lumen. Said occlusions impair further deployment of Onyx distally. Thus, the use is patentably novel.

The present invention can take several embodiments. Referring now to FIG. 1, the current invention is composed of a catheter 10, a side hole 20, a distal end hole 40, a proximal catheter hole 80, and an optional wire 60. This embodiment takes a form similar to the design of the Transfrom (Stryker) and/or the Hyperglide/Hyperform (EV3/Covidien/Medtronic) balloon. FIG. 2 shows the embodiment of FIG. 1 with the addition of a detachment (or breakaway) element 110 between proximal end hole 80, side hole 20, and tapered end 30. Detachment element 110 may be a coupling, a score, a stressed area, or any other suitable means for detaching the distal end of catheter 10 using perpendicular force provided by the proximal end of the catheter 10. FIG. 3 shows the embodiment of FIG. 2 of the present invention without the wire 60.

However, the present invention as envisioned by embodying the general design of the Transform (Stryker) and/or the Hyperglide/Hyperform (EV3/Covidien/Medtronic) has no balloon enclosing contrast. It has a larger inner diameter until the end of the side hole, approximately 0.011 in., and smaller thereafter, approximately 0.008 in. Initial injections with a 0.008 in. wire in place allow the Onyx or other fluid to “fill” that segment of the vessel at the side hole, forming the “plug”; and will have a wire that will completely obstruct the inner lumen the distal tip of the micro-catheter while Onyx 34 (or equivalent) is injected, preventing obstruction of the distal tip of the micro-catheter from stagnant Onyx that would otherwise be contained in it.

In the basic embodiment, if less than two minutes are allowed from initial ‘plug’ injection until subsequent ‘push’ injections, the Onyx in the distal tip of the catheter would not normally precipitate fully, and thus does not obstruct the catheter.

The wire can then be removed, allowing flow out the tip. In the event that due to some anatomical difficulties, an advancing a wire that far out is not desirable because of tortuosity and frail vessels that can cause perforation of the vessel; in other instances the wire can get stuck in the catheter after injection of Onyx 34, thus preventing the wire's removal and preventing the proper delivery of the Onyx 18 injection. In such cases, alternate embodiments of the present invention should be considered as preferred for those situations.

Referring now to FIG. 3, another embodiment in which the single lumen of the present invention takes the form similar to the design of the distal-most portion of the balloon lumen of the MicroVention Scepter balloon and/or the Micrus/Codman/Depuy Ascent balloon, the portion encompassing the ‘valve’ beyond the balloon. However, the present invention embodies the general design of the MicroVention Scepter balloon and/or the Micrus/Codman/-Depuy Ascent balloon, but as the present invention does not have a balloon, no balloon prep is necessary.

The present invention has a side hole in the lumen whereas the MicroVention Scepter balloon and/or the Micrus/Codman/Depuy Ascent balloon have balloons with a dual lumen design. The preferred embodiment of the present invention has a small channel that can be made at the end of the single lumen catheter, as that which only allows air to go out of it but does not allow contrast out in the Scepter, said channel incorporates one or more elements that allow dimethyl sulfoxide or less viscous Onyx 18 through, but NOT Onyx 34—which would instead flow out of said side hole.

As incorporated into the present invention, said mechanism is not dependent upon particle size. The difference between Onyx 34 and Onyx 18 is not related to particle size, but rather the concentration of the suspended material (8% vs. 6%). Thus, the concentration results in different viscosity, but does not differ in particle size, in the various formulations of precipitating hydrophobic inject-able liquid.

A modification of the second embodiment uses a particular size/diameter and shape of a channel distal to the side hole that would allow passage of dimethyl sulfoxide (DMSO), and would allow passage of the less viscous embolic agent such as ONYX 18, but would not allow passage of Onyx 34 or the like.

Referring now to FIG. 4, the third embodiment of the present invention is composed of a catheter 10, a side hole 20, a distal end hole 40, a proximal catheter hole 80, and governing element 90. This embodiment a governing element 90 such as a flap valve, a “push” diaphragm, or other device capable of stopping Onyx flow from deploying out of the end hole 40 and thereby diverted to side hole 20. This embodiment incorporates the design of the Strata® valve, or other valve. Using a standard micro-catheter with a valve on the inner lumen of the micro-catheter at the distal end of the side hole, that can be closed by a magnetic field created by an electric current applied after infusion of dimethyl sulfoxide.

Said valve can be opened by removal of the electric current (after the Onyx 34 or similar is injected and an adequate proximal “plug” is created). In particular, said valve contains a magnet or other means inside the valve mechanism that allows the neurosurgeon to change the opening setting of the valve.

Alternatively, non-magnetic micro-value technology may be employed. For example, a solenoid micro-valve may be employed. Said solenoid micro-valves use a coil of wire wound in a helix, like a compressed spring. A magnetic field is created by passing current through the solenoid. The placement of a metallic object within the coil and the ability to vary the current, allows said object to move. In short, a solenoid micro-valve is simply a solenoid with an actuator inside of it. The actuator is situated above the channel of a micro-fluidic device and pushes down on the ceiling of the channel to collapse it and obstruct its flow. Valves opened and closed by other compatible mechanisms can be used as well.

The valve can be semi-permeable/selectively permeable, or non-permeable. Said valve can be fixed and not able to open with selectively permeable material. Any valve which can open does so in response to pressure, magnetic field, or a combination thereof, and/or other triggers.

The third embodiment of the current invention is not anticipated because the Strata® device includes a valve used to regulate the flow of cerebral spinal fluid (CSF) in a shunt system. The embodiment set forth above uses valves to regulate deployment of intravascular liquid embolic agents. Thus, while the Strata® device has some of the same elements as the present invention, said elements are employed for non-obviously different purposes.

Referring again to FIG. 4, side hole 20 can be governed by the use of a semi-permeable membrane flap across the diameter of the catheter at the distal end of side hole 20. Said semi-permeable membrane is a type of biological or synthetic, polymeric membrane that will allow certain molecules or ions to pass through it by diffusion. In said embodiment, the side-hole closing flap may be used to cover end-hole 40, thus preventing Onyx from deploying through the distal catheter 10 and end hole 40, thereby directing it through side hole 20.

In particular, said flap is placed within the catheter 10 at the distal end of the side hole 20, such that a lumen wire can push it aside, but it will revert to its original (closed) position when said wire is removed. In some embodiments, said flap is permeable to liquid dimethyl sulfoxide, but not to any Onyx, but once a certain pressure is built up from the plug obstructing the side hole, the pressure of the Onyx column will push the flap open, and allow distal flow of Onyx.

FIG. 5 shows the embodiment of FIG. 4 with the addition of a detachment element 110 between proximal end hole 80 and side hole 20.

Alternatively, the present invention incorporates the governor (or valve element) 90 such as that taught by “Bi-stable micro-valve and micro-catheter system” (U.S. Pat. No. 6,638,21 B2) or a similar valve. The present invention in a preferred embodiment employs a bi-stable micro-valve 90 of shape memory material that is operatively connected to a micro-catheter at the distal end of side hole 20. Said bi-stable micro-valve 90 includes tips that can be closed off until said valve 90 is in the desired position. Once it is in position it can be opened and closed. The system uses heat and/or pressure to open and close the micro-valve 90.

Referring now to FIG. 6, a further embodiment of the present invention is composed of catheter 10, end hole 40, proximal hole 80, and zone of hydrogel 100 coating the exterior circumference of catheter 10 proximal to end hole 40. In this embodiment, no side hole is required. Hydrogel zone 100 extends approximately 1 mm. to 3 cm. from the distal end hole, with a preferred extension of approximately 3 mm. to 10 mm. from the end hole.

FIG. 7 shows the embodiment of FIG. 6 with the addition of a detachment element 110 proximate to the proximal extent hydrogel zone 100.

Although the invention has been described in detail in the foregoing embodiments for the purpose of illustration, it is to be understood that such detail is solely for that purpose, and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention, except as it may be described by the following claims. 

I claim:
 1. A unitary single-lumen micro-catheter comprising: an elongated tube defining a single lumen therethrough, said lumen comprising at least one side hole disposed proximal to a distal end hole, wherein said at least one side hole is flush with inner and outer surfaces of said elongated tube, a proximal hole, and a governing element distal to said side hole, and proximal to said distal end hole, a detachment zone distal to said proximal hole and proximal to said side hole, a microwire dimensioned to plug said distal end hole disposed within said lumen, and wherein said detachment zone is a rejoinable coupling element capable of detachment from and reattachment to the micro-catheter.
 2. The micro-catheter of claim 1, wherein said governing element is attached to the distal end of said side hole.
 3. A method of using the micro-catheter according to claim 1 for endovascular treatment of arteriovenous malformations and arteriovenous fistulas, comprising the steps of: (a) insert said micro-catheter with governing element in open (flow-through) position; (b) advancing said catheter to a target vessel proximal to a target lesion; (c) injecting a liquid embolic solvent into said target lesion; (d) closing governing element; (e) injecting additional said liquid embolic to form a plug around said side hole between said detachment zone (when present) and said distal end hole (f) stopping injection when opening of target lesion is covered; (g) waiting until said plug is partially solidified (h) opening said governing element (i) injecting additional said liquid embolic solvent has penetrated said target lesion; (j) stopping injection when optimal amount of said liquid embolic solvent is present in said lesion; and (k) removing said micro-catheter.
 4. A method according to claim 3, comprising the step of: arresting flow when said governing element is in closed position, when at least one of decreased blood pressure, a proximal balloon, and pharmacologic cardioplegia is present. 